Casus Belli
by Kyilliki
Summary: Carlisle, Caius, and the opposite of a pleasant conversation between friends.


**CASUS BELLI**

**CHARACTERS: **Carlisle, Caius

**RATING: **T, with no warnings. Everyone is on their best behaviour here.

**AUTHOR'S NOTE:** As is the case with many excellent requests, this one from an anonymous source. They wanted to read about a conversation between Caius and Carlisle. These two characters are understandably not fond of each other, but I did manage to mash them together for some 1,700 words. I hope this is to your satisfaction, nameless internet denizen!

This fic takes place during Carlisle's stint as a houseguest in Volterra. _Casus belli _is a Latin idiom, refering to the justification for acts of war.

* * *

Stepping into the library muffled Carlisle's thoughts with a dusty shroud. It was a windowless chamber, a basilica's nave with rib vaulting rising high. The architecture mimicked a leviathan's insides, its belly swollen with the swallowed debris of a thousand shipwrecks. The shelves dated from every century, their contents likewise. A half-dozen curators tended to these collections, Aro had explained, gesturing to river-clay tablets nestled next to fresh folios, and there was no teaching them a standardized system. Much easier to simply navigate by memory and scent.

Today, Carlisle waded through torchlight, seeking—he was not sure. As a human man, cloud-eyes and trembling, he had read cautiously, quick to prevent any impious notions from brushing against the very periphery of his mind. This place was a temple to the ungodly, each fragment of parchment vetted by the proudest and most terrible of tumbling angels. Fear—of sin and a blood-eyed downfall—slowed his choices.

There was a rustle of paper from the stacks. Carlisle had been in the company of other immortals for long enough to recognize the gesture for what it was: a polite way of announcing one's presence. Curious, he padded closer. Meeting Marcus or Aro among the shadows was occasionally a welcome interlude.

He had not expected Caius. In the deep and peaceable dark of Carlisle's mind, he cradled the belief that there were two sorts of people in the world: those who read, and those who frightened him. This other brother was an abrupt and messy overlap, a blurring of the borders. Nonetheless, there he was, pinched and pale and unsettling. He sat, perfectly rigid, in a stiff-backed chair winged by shelves.

Caius nodded in curt acknowledgement, then set aside his book— indigo-covered, hand-penned, delicate—and moved to rise. So outspoken in the performance of his duty, he seemed to prefer silence.

"Please, I did not mean to disturb you," Carlisle said hastily, his voice like starved reeds, displeasing youthful to his own ears.

"I was intending to leave." It was a courteous reply, but devoid of sincerity.

"Have I given you some reason—any cause—to dislike me?" He examined his list of past offences, small missteps and miniature linguistic disasters, before deciding that nothing there could have affronted Aro's left hand.

"I do not trust you," Caius said easily. Almost pleasantly, as though it were a fact, but one of no consequence. Although he remained in his seat, too mannered to depart while being addressed, impatience lined his limbs.

Carlisle was a child once more, kneeling for hours, splinters in his shins, as atonement for spinning some fanciful tale. _You shall not tell lies_, his father had said, with mouth and callused palm and hissing switch. "I have always been honest," he whispered.

"You are open about your convictions," his companion agreed. "But you have no respect for the law, mine or otherwise."

"I have not broken the rules," Carlisle said swiftly. Certainly, he did not look local, but that had only earned him a string of stares when he wandered through the city, not cries of 'monster!' and torch-bearing mobs.

Caius nearly rolled his eyes at the child's stubborn literalism. "You wish to live among humans. Each day of your continued existence is unlawful."

"I don't intend to reveal myself." Suddenly, sickeningly, Carlisle imagined someone grasping his hand and feeling no heartbeat thrumming beneath their touch, or perhaps asking why his irises danced from amber to jet and back again.

The ghostly man grinned, summoning that feral smile with too many teeth displayed in naked threat. "Frankly, I do not care about your intentions. Someone will discover what you are eventually. You are not entitled to undo two thousand years of my efforts."

Carlisle crumpled. "I have no place among immortals. I cannot simply _hide_ from humanity," he said. Melancholy, lonesome yet inviting, had won him many arguments with Aro.

"And yet, here you stand."

It was a long visit for someone with no formal status in the ranks, and Caius did not like it. Gossip about Aro's perverse pet was already unseemly, and spreading with every passing month. A title and crest demanded some pretense of morality, no matter what occurred behind barred doors. In a moment of foolish sentiment, he admitted that the he pitied the little witch twins as well, shoved aside without ceremony as soon as Aro found this new, golden toy of his. Pragmatism took hold once more. An irate Jane was a matter for concern.

"You are exceptions, your brothers and yourself," Carlisle said. The denizens of Volterra were too jagged to patch the holes punched through his chest, but they were better than nothing.

"In what sense?"

"You are civilized. You do not mindlessly destroy. There are some things you wish to build and preserve. Those are not _normal_ impulses amid our kind." The litany of reasons came out too quickly, as though it had been rehearsed minutes before a performance, but Carlisle didn't care. Remembering his time amongst nomads, gleeful, alarming beasts from first to last, turned his words to water.

That evident softness made Caius bite away a smirk. A vampire with such fragile sensibilities could only hope to survive by dependence on others. At least Carlisle had the grace to call it friendship. "We feed on humans," he said instead, half non sequitur, half trap.

"Unfortunately," he agreed, unsure where the conversation was going. Caius, it seemed, employed the same evasions that Aro did, while lacking the mannerisms to make it playful.

"All the trappings of our civility—literature, art, wealth—are stolen from our meals. The castle itself belonged to a noble family, famed for their benevolence. You will find their deaths attributed to fever, because we happened to record those histories." Caius allowed himself to linger over the more amusing memories of carnage and acquisition. Not so very long ago, Aro (and Marcus, when he felt slightly less mournful than usual) cheerfully massacred entire monastic orders while robbing them of their books and treasures. The marauding Northmen who ravaged England's coast owed a portion of their fearsome reputation to scholarly vampires.

"You are very willing to take advantage of human suffering, Carlisle Cullen," he said.

"I inflicted none of it," he said.

"How true. But you do not stop us either."

"I cannot stop you." Carlisle had once remarked, gently and in the vaguest of terms, that feeding on imprisoned humans was cruel, in the hearing of all three brothers, the wives, and half the Guard. He had no interest in repeating the experience. The glares alone were promised death.

"But you can leave, and have no further part in it." Caius let his gaze travel from the splash of colourless gems pinning Carlisle's cravat to the pale gold circling his fingers. "A man who speaks of his ideals so fervently and often, but then forsakes them for trinkets—he is not loyal," he said, and his voice was condemnation itself. Later, he was certain, his wife would muffle her laughter against his shoulder and imply that Aro's theatrics were contagious, but in this moment, his anger lacked artifice.

"What I learn here—from these books—it will help me save lives. It is worth remaining here, for that alone," Carlisle spoke proudly, each word weighted with rectitude. This was the _right _answer, the one he kept in his pocket and thumbed as the screams spread from the eyrie of the feeding chambers. The shiver of his shoulders could only be noticed by those looking for flagging strength.

"As a physician. Very noble, I'm certain. Why has it taken you fifteen years to read the small amount of material we have pertaining to your discipline? A mortal could accomplish the task in less time." He could not tell whether Carlisle believed his own justifications, but challenging them was viciously _fun_.

"Is my presence so offensive?" The question was red and weeping, a wound made of words. Carlisle, it appeared, could not imagine being unwelcome.

"Yes," Caius said.

"You—you are hardly in a position to judge me." Carlisle did not know that he was capable of ferocity—steel, yes, and conviction, but never the desire to conquer. "Your justice is an excuse for cruelty. For wanton slaughter. You do not care about the outcomes of your actions."

He could not recall loathing anyone as much as he did Caius, when he did not accept the challenge.

"You have met nomads," the white-haired man said, in a tone that was both leisurely, and a stalking, hungry thing.

"Yes."

"In your experience, have they responded well to reason?"

"That does not mean that they are deserving of death," Carlisle hissed, too familiar with executions, pleasure distorting the paper masks of his hosts' faces. He refused to believe that these were his only choices—the anarchic and feral, or the genteelly brutal.

"What would you have me do in the place of ending them for their crimes?" Caius wondered, truly intrigued for an instant.

Carlisle considered the possibilities. These were creatures that could not be constrained. Could not be taught, even. "Forgive them. Offer them another chance." He knew there was no practicality in his offering, and made it nonetheless.

"I think not. The whole world would know of our kind within a decade. Imagine how many of your precious humans would die if men like your father were believed," he countered. Aro had always found witch-hunts fascinating. The chatter of mortal minds crystallized into something spiked and pure and terrible. They murdered one another with such exquisite joy, such orgiastic righteousness, the dark-haired man cooed, fingertips trembling in anticipation of another Alec, an improved Jane. Caius was more inclined to ponder the death toll, and what that would do to vampire hunting patterns in the region.

"Surely no more than you yourself kill," the golden-eyed man countered.

"Every choice you make, Carlisle Cullen, is only a possibility because of what my brothers and I have done. Or whom we've killed, however you prefer to phrase it." Caius considered pressing the point, but held his peace. His brother would be displeased if he personally drove away the entertainment. "This has been a pleasant conversation," he said, with mild detachment that was almost a mockery of Marcus. "I cannot see why we did not have it sooner."

Caius did not bother with farewells as he swept past Carlisle. The younger man would make a formal exit soon—give him a year, maybe two—and he intended to ration his pleasantries until then.


End file.
